@Hitesh Gupta Thanks for asking question! There was a recent update to the Email Communication Services: you can no longer create a new MailFrom address or enable engagement tracking if you are on the default throttling limit.
Could you please confirm if you are currently on the default throttling limit?
If so, you can request an increase in the throttling limit as detailed in the documentation here:
Azure Communication Services Email Service Limits. Once the limit is increased, you will be able to use these features.
You can request to increase the sending volume limits. Submit a support request to raise your desired email sending limit if you require sending a volume of messages exceeding the rate limits.
Email quota increase requests aren't automatically approved. The reviewing team considers your overall sender reputation, which includes factors such as your email delivery failure rates, your domain reputation, and reports of spam and abuse when determining approval status.
Also Note that- Email quota increase requests may take up to 72 hours to be evaluated and approved, especially for requests that come in on Friday afternoon.
Hope this helps. Please let us know if further query or issue remains.